1. Field of the Invention
The present invention relates to a thermostat-controlled containment cell for a sample, suitable notably for a measuring device such as a nuclear magnetic resonance (NMR) spectrometer, to a NMR type measuring device including the cell and to a method of implementation.
2. Description of the Prior Art
Nuclear magnetic resonance (NMR) measuring devices conventionally comprise magnets and coils placed in the air gap of the magnets. An oscillating electric field (generally in the radio frequency range) is applied to the sample subjected to the magnetic field by connecting the coil to a variable-frequency signal generator, and the response of the sample to the excitation signals is recorded. In order to stabilize the magnetic field created by the magnets, their temperature is stabilized by establishing a forced air circulation and by interposing between the magnets and the excitation coil a cooling circuit in which a fluid circulates.
Within the scope of measuring operations, it is useful first to bring the sample to a predetermined temperature. This is for example the case for laboratory calibration of measurements performed by means of NMR logging sondes at various depths of underground zone exploration wells. It is therefore possible to place the sample for example in a thermoregulated vessel prior to transferring it in the air gap when measurements are to be performed. However, it is then difficult to maintain the sample at a really constant temperature. The solution of exposing the sample in the air gap, to a controlled-temperature gas stream is generally not satisfactory.